1 files changed, 36 insertions, 0 deletions
diff --git a/zen/com_error.h b/zen/com_error.h
index 2ba76c0f..4546bd8a 100644
--- a/zen/com_error.h
+++ b/zen/com_error.h
@@ -16,6 +16,29 @@ namespace zen
 std::wstring generateErrorMsg(const std::wstring& input, HRESULT hr);
 std::wstring formatWin32Msg(DWORD dwMessageId); //return empty string on error
 
+class ComError
+{
+public:
+    explicit ComError(const std::wstring& msg, HRESULT hr = S_OK) : msg_(hr == S_OK ? msg : generateErrorMsg(msg, hr)) {}
+    const std::wstring& toString() const { return msg_; }
+
+private:
+    std::wstring msg_;
+};
+
+#define ZEN_CHECK_COM(func) ZEN_CHECK_COM_ERROR(func, #func) //throw ComError
+/*Convenience Macro checking for COM errors:
+
+Example: ZEN_CHECK_COM(backupComp->InitializeForBackup());
+
+Equivalent to:
+{
+    HRESULT hrInternal = backupComp->InitializeForBackup();
+    if (FAILED(hrInternal))
+        throw ComError(L"Error calling \"backupComp->InitializeForBackup()\".", hrInternal);
+}
+*/
+
 
 
 
@@ -202,5 +225,18 @@ std::wstring generateErrorMsg(const std::wstring& input, HRESULT hr)
     }
     return output;
 }
+
+
+#define ZEN_CHECK_COM_ERROR(func, txt) \
+    {                                  \
+        HRESULT hrInternal = func;     \
+        if (FAILED(hrInternal))		   \
+            throw ComError(L"Error calling \"" ## ZEN_CONCAT_SUB(L, txt) ## L"\".", hrInternal); \
+    }
+
+#ifndef ZEN_CONCAT //redeclare those macros: avoid dependency to scope_guard.h
+#define ZEN_CONCAT_SUB(X, Y) X ## Y
+#define ZEN_CONCAT(X, Y) ZEN_CONCAT_SUB(X, Y)
+#endif
 }
 #endif //COM_ERROR_HEADER